The present invention relates to a passive system for identifying remote objects using pulsed radar principles wherein a coded transponder associated with the object is energized by radio frequency interrogator burst pulses to produce coded identification signals which are used to identify the object. The system has particular utility for identifying livestock and the like.
Many techniques to detect or identify objects have been developed in the past with applications to industry, inventory control, security, safety control, etc. Individual object identification has become more complex because a specific identification code is desired as opposed to simply the presence or absence of a detection signal. Optimally, a specific identification code must be sent back from the source to the interrogation device.
The present invention was developed to satisfy the need to uniquely identify many animals in the livestock industry. Animal identification is the first step towards an automatic herd management system, which will make it possible to know individual cow production, feeding level, animal health and to keep a daily record.
A transmission link must be established from the animal to transfer the coded identification signal. While a number of different types of transmission links are possible including optical, audio, and laser beams, and electromagnetic waves, radio transmission waves have been selected as being the most cost effective. The identification system of the present invention utilizes passive transponders which are associated with the livestock to be identified. The transponders are passive, as opposed to active, in that no integral power source is provided. Passive transponder techniques are most attractive due to their long life and low cost characteristics. Transponder design utilizing circuit integration techniques of hybrid technology can greatly reduce initial costs.